.w {
    width: 1200px;
    margin: 0 auto;
}

* {
    margin: 0;
    padding: 0;
}

li {
    list-style: none;
}

.clearfix:after {
    content: "";
    height: 0;
    line-height: 0px;
    display: block;
    visibility: hidden;
    clear: both;
}

.clearfix:after {
    *zoom: 1;
    /*针对IE6/IE7*/
}